During a 2-year period, 250,000 Florida largemouth bass fingerlings were stocked among the endemic northern largemouth bass population of Tradinghouse Creek Reservoir (1985 = 185/ha, 1986 = 123/ha). We used electrophoresis to estimate proportions of Florida, northern, and Florida x northern intergrade largemouth bass within pre-stocking, stocking-year, and post-stocking year cohorts. Ages of largemouth bass were determined by examination of whole otoliths. The proportion of Florida phenotypes within the stocking-year cohort was not increased when the stocking rate was more than 50/ha greater. Stocked Florida phenotypes comprised 6% and 25% of the 1985 and 1986 cohorts, respectively, at age 1. Implementing a less restrictive harvest regulation accelerated introgression of the Florida genome by providing sizerelated, selective harvest of larger, northern largemouth bass. During the 2 year period from 1987-1989, Florida and Florida X northern phenotypes increased from 22% to 78% of largemouth bass sampled.
